几类典型结构陶瓷材料的冲蚀磨损行为研究

A STUDY ON EROSION EROSION BEHAVIOR OF CERTAIN TYPICAL STRUCTURAL CERAMICS

研究了几类典型结构陶瓷材料,如Al_2O_3,SiC,Si_3N_4陶瓷,Al_2O_3-ZrO_2系相变增韧陶瓷(ZTA,TZP)和SIC_w/Si_3N_4系晶须补强陶瓷(WRSN)在90m/s下的冲蚀窘损性能,以及其与材料性能(硬度,断裂韧性)和冲蚀条件(粒子硬度,冲击角度)之间的关系,分析了冲蚀磨损机制。陶瓷材料的低角冲蚀磨损机制主要包括:研磨状损伤,犁沟状微切削损伤和晶粒剥落。低角冲蚀窘损亭随材料硬度的增加而降低。高角冲蚀窘损机制主要为Hertzian应力作用下的脆性断裂和由表面裂纹的扩展与贯穿而引起的群晶剥落。高角冲蚀磨损率随材料韧性的提高而降低。ZTA和WRSN复合材料表现出较低的冲蚀磨损率,这是由于其中相变增韧机制和晶须补强机制耗散了裂纹扩展能,阻碍了裂纹扩展与贯穿,从而抑制晶粒群体剥落。

Solid-particle erosion of a series of typical structural ceramics was investigated at room temperature at 90m/s by using SiC and SiO_2 abrasives. The systems chosen are Al_2O_2, SiC, Si_3N_4, Al_2O_3-ZrO_2 and silicon nitride reinforced with 20％ (vol) SiC whisker. The erosion resistance depends on erosion conditions and mechanical properties and microstructurc of ceramics. The main erosion mechanisms at low impact angle are grinding-like abrasion, minor chipping and surface grain peeling in which grains are abraded one by one or in a cluster. Increasing the hardness results in an improved erosion resistance at low angle. At high angle erosion is induced by the formation and propagation of Hertzian cracks, lateral cracks and radial cracks under driving forces imposed by the impact particle which cause the peeling of surface grains. The erosion resistance is increased by using whisker reinforcement and zirconia toughening which constrain crack propagation by whisker bridging and martensitic transformation.